Two-cycle engine



Sept. 12, 1967 B W..FOSTER TWO-CYCLE ENGINE Filed Sept. 30, 1965 5 Sheets-Sheet l I I?! H H] I W3 IIVVEIVTOR BERRY W- FOSTER BY Ow) ATTORNEYS Sept. 12, 1967 9. w. FOSTER 3,340,354

TWO-CYCLE ENGINE Filed Sept. :50, 1965 3 Sheets-Sheet :2;

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AT TORNEYS Sept. 12, 1967 B. w. FOSTER TWO-CYCLE ENGINE Filed Sept. 30 1965 3 Sheets-Sheet 5 52 INVENTOR BERRY n4 FOSTER B) I ATTORNEYS United States Patent 3,340,854 TWO-CYCLE ENGINE Berry W. Foster, Santa Monica, Calif. (2415 Thomas Ave., Redondo Beach, Calif.

' Filed Sept. 30, 1965, Ser. No. 491,527

24 Claims. (Cl. 12332) ABSTRACT OF THE DISCLOSURE A precombustion chamber is provided adjacent to the head end of a cylinder of a two-cycle engine, with firing means and in communication with the cylinder through a nozzle located near the outer periphery of the cylinder head and directed to expel heated gases from the nozzle into the cylinder from the precombustion chamber in a circumferential direction. Thus, the heated gases create a vortex moving helically along the cylinder toward sleeve exhaust ports, while burning the cylinder gases and sending them along the helical vortex path. Flow means enable the air to fiow from the air intake means into v the center of the vortex and distant from the head; the

air intake means and flow means may comprise a head on the piston and a port therethrough, or the air intake means may be a sleeve port further from the head end than the exhaust port. Specific structures to accomplish this operation are described.

This invention relates to improvements in two-cycle engines.

One reason why high efficiencies have been difficult to obtain from two-cycle internal-combustion engines has been that scavenging has generally been incomplete and ineflicient.

The commonest scavenging system for two-cycle engines has been loop scavenging, in which sleeved ports were uncovered by the piston when the piston was near or at the crank end; an exhaust port opened first to let hot exhaust gases blow down to the scavenging pressure, and then an intake port opened to send in a fresh charge of air. This fresh charge was deflected up toward the cylinder head and then flowed through a loop path to force most of the burnt gases out of the engine cylinder through the exhaust port. Loop scavenging, though mechanically simple, was inefficient, because the fresh charge of air mixed with the burnt gases and was unable to blow all the gases out of the corners, especially near the cylinder head. As a result, the charge of air trapped in the engine for the compression process was not completely fresh. Further, a large proportion of the engine stroke was required to complete the scavenging process. Because of these factors, the effectiveness or specific power of loop-scavenged engines was only about 60% of what it should be in comparison with a comparable four-cycle engine, and its efficiency was much less that of a comparable four-cycle engine.

Somewhat increased performance and improved specific power output have been obtained from two-cycle engines by providing, in their head, poppet valves in addition to the sleeve ports that were uncovered by the piston at the crank end. This poppet-valve and sleeve port system provided unidirectional scavenging, which supplied the cylinder with a fresh charge and imparted an efiiciency approaching that of a comparable four-cycle engine. The difiiculty has been that the poppet valves, rocker arms, tappets, cams, gears and other parts required by such systems have heretofore made the resultant engine much more complicated mechanically.

One object of the present invention is to provide a two-cycle engine having performance and efiiciency that are as good as those of a comparable four-cycle engine, while at the same time being mechanically much simpler than either a four-cycle engine or a two-cycle engine of the heretofore-known poppet-valve type used for unidirectional scavenging. The invention makes it possible to provide an engine with a scavenging system as mechanically simple as the loop-scavenged two-cycle engine; a somewhat better system of this invention is only slightly more complicated than the loop-scavenged engine and is much less complicated than the prior-art engines with poppet-operated valves.

An important feature of my invention is that during scavenging a vortex is generated with an eye at the center of rotation, that center lying along the axis at the center of the cylinder and parallel to the line of motion of the reciprocating piston.

Another importantfeature .of the invention is a novel fluid pumping means which accelerates the flow of the fresh charge of air into the cylinders and expands the hot gases to a lower pressure in the cylinder before they are exhausted. This feature enables 20% to 40% more shaft power to be obtained for a given amount of fuel energy added. The additional expansion is accomplished by having the intake and exhaust ports remain open during the first half of the piston stroke toward the head end, so that the cylinder can be scavenged and charged with fresh air during this portion of the cycle. During the last half of the piston movement toward its head, the exhaust ports and intake ports are closed, and air is compressed. Combustion follows, employing either spark ignition or fuel injection. During the expansion stroke of the piston toward the crank end, the exhaust and sleeve ports remain closed until near the crank end, and then the exhaust port is opened. As a result, the hot gases expand and do work on the piston for about twice the distance that compression work is done on the air.

This invention may be used in a multi-cylinder engine as well as a single cylinder engine.

Other objects and advantages of the invention will appear from the following description of some preferred embodiments.

In the drawings:

FIG. 1 is a fragmentary isometric view of a portion of a two-cycle engine embodying the principles of the invention, showing one end of a cylinder and a portion of its piston during a relatively early portion of the expansion stroke.

FIG. 2 is a similar view of another portion of the cylinder and piston of the same two-cycle engine in a later position during the exhaust-and-intake stroke.

FIG. 3 is another drawing similar to FIG. 2 of a somwhat modified form of engine in approximately the ame position as in FIG. 2, but with a sleeve intake valve instead of a valve in the piston head.

FIG. 4 is a fragmentary enlarged view in elevation and in section of the piston and a portion of the cylinder of the valve of FIG. 2 slightly before the piston reaches its crank-end position.

FIG. 5 is a fragmentary view in elevation and in section on the scale of FIG. 2 showing the piston with its head valve closed.

FIG. 6 is a view in section taken along the line 6-6 in FIG. 4.

FIG. 7 is a fragmentary view in elevation and in section similar to FIG. 4 of a modified form of the invention and showing the relationship between certain dimensions.-

gases flow through the piston exhaust passage and the exhaust port.

FIG. is a view similar to FIG. 9 showing the engine in a succeeding position with the piston closer to the cylinder'head and past the half stroke position, where the counter mass has forced the intake valve in the iston head to close.

FIG. 11 is a view similar to FIG. 10 showing further compression of the trapped gas.

FIG. 12 is a fragmentary view in perspective and partly in section showing gas expansion with the ports closed.

FIG. 13 is a view similar to FIGS. 8-11 showing the piston in its expansion stroke approaching the opening of the exhaust sleeve ports.

FIG. 14 is a pressure-volume work diagram of an Ottocycle engine employing the principles of this invention showing the added energy, in the shaded area, obtained by further expansion of the gases.

FIG. 15 is a temperature-entropy heat diagram of the engine of FIG. 14 showing the added energy in the shaded area.

FIG. 16 is a diagram like FIG. 14 of a diesel-cycle engine embodying the principles of this invention.

FIG. 17 is a diagram like FIG. 15 for the diesel-cycle enging of FIG. '16.

Referring first to FIGS. 1-6, a piston 20 reciprocates in a cylinder 21, which has a head 22. A precombustion chamber 23 located in the cylinder head 22 has a nozzle 24 for directing high-velocity hot gases from the chamber 23 in a circumferential direction, so that they flow through the cylinder 21 in a helical spiral path generating a vortex V that has its center of rotation C along an axis that is also the center line of the cylinder 21. A fuel injector 25 may be used to inject fuel into precombustion chamber 23 at the desired firing time, or spark ignition may be used if desired.

At the crank end of the cylinder 21, exhaust ports 26 are uncovered by the piston 20 when it gets near to the crank end. An air-intake port 27 may be located in the head 28 of the piston 20 and may be opened and closed by a valve 30. The valve 30 is preferably rigidly secured to the piston 20; so the valve 30 moves with it, the intake port 27 being mounted on a plate-and-cylinder member 32, which is slidably mounted in a bore 33 in the piston 20 and moves with respect to the piston 20 to open and close the intake port 27. When the intake port 27 is closed, the plate 32 moves with the piston 20 as though it were a rigid part of it. The cylinder-plate 32 may have a conical surface 34 which seats on a mating surface 35 of the valve 30 when the port 27 is closed.

The cylinder-plate 32 may have secured thereto one (or more) rod 36, and it preferably has two such rods 36, which may be identical. One end of each rod 36 is joined to the plate 32 and moves with it, while the other end of the rod 36 may be connected to a small auxiliary piston 37, which thus moves with the rod 36 and the plate 32. The piston 37 may be reciprocated (by movement of the piston 20) in an axuiliary cylinder 38, which may be filled with gas, such as air, to act as a pneumatic spring for opening the ports 37 when the piston 20 approaches its crank end. The auxiliary cylinder 38 may be rigidly secured to the cylinder 21, with the piston 37 reciprocating in it as the platecylinder 32 is forced to follow the piston 20. The plate-cylinder 32 may be provided with a stopping means 39 and 40 consisting of levers 41 and 42 extending through holes 43 and 44 in the plate cylinder 32 which restricts its motion with respect to the piston'20. The levers 41 and 42 are parts of counter masses 45 and 46 which pivot on the piston pin 47. A connecting rod 48, which may be driven by the engine crankshaft (not shown) also pivots on the piston pin 47 The piston pin 47 has its bearing on the piston 20. If desired, a mechanical spring may be used in place of the pneumatic spring '38, 38.

FIG. 3 shows an alternate design in which the piston 20 has a solid head 49 and where there is a sleeve intake port 49a.

As the piston 20 moves from its crank end to the head 22, air that is trapped in the engine cylinder 21 is compressed therein and in the precombustion chamber 23. At the end of the compression stroke, when the piston 20 is at or near its head 22, the fuel injector 25 injects fuel into the precombustion chamber 23. The fuel explodes and burns with the air in the precombustion chamber 23 by a substantially constant volume process. As a result, the pressure in the chamber 23 is increased to a level above the pressure in the main cylinder 21. The hot highpressure gases then expand through the nozzle 24 at a high velocity in a circumferential direction with a helical spiral path. Thus in FIG. 1, the piston 20 is moving down on its expansion stroke, and the hot combustion gases are expanding through the precombustion chamber nozzle 24 along in a helical spiral path that generates the vortex The helical spiral path of the high velocity hot gases generates the vortex V having its center of rotation C along the axis or center of the cylinder 21, and this vortex forces the air trapped in the cylinder 21 to mix with the hot combustion gases and to complete the combustion process in the cylinder 21. The pressure at the eye C of the vortex V is reduced by this action, and the centrifugal force of the gases increases the gas pressure around the edges directly in proportion to its radius. When the exhaust sleeve port 26 is open, as in FIGS. 2 and 4, the rotating momentum of the vortex gases forces them radially outwardly and causes them to follow the wall of the cylinder 21 and to flow out the exahust port 26 when it is uncovered by the piston 20. The rotating momentum or centrifugal force supplements the mean gas pressure and forces the gases to exahust fasted than they otherwise would.

In FIGS. 2 and 3, the piston 20 is at the crank end of its stroke. The reduced pressure at the core C of the vortex V helps to suck in the intake air, which (in FIG. 2) is directed into the center of the cylinder 21, through the intake port 27 in the piston head 28. In FIG. 3, the sleeve intake ports 41 are uncovered by the piston 20 when it is near its extreme crank end.

As shown in FIGS. 2, 3, and 4, the intake air is directed into the center C of the vortex where the air pressure is reduced. The reduced pressure at the core C of the vortex V helps to suck the fresh air into the cylinder 21 faster than it would otherwise flow in. The pumping forces of the vortex scavenging means therefore supply the engine cylinder 21 with a fresh charge of air which includes very little or practically no burnt gases.

As the piston 20 approaches the crank end, the sleeve port 26 is opened; so the hot burnt gases will flow out the exhaust port 26 to let the exhaust gases blow down and leave the cylinder 21 gases at scavenging pressure.

In FIG. 4, the piston 20 has uncovered the exhaust sleeve ports 26, and the intake port 27 is opened by the pneumatic spring 37, 38 when the spring 37, 38 force is greater than the cylinder 21 gas pressure force on plate 32; a little earlier, the hot burnt gases started to flow out the exhaust port 26 to let the cylinder gases blow down to the scavenging pressure. With the piston 20 near the end of its down stroke, the gas pressure in the cylinder 21 was reduced sufficiently so that the pneumatic spring mechanisms of the intake valve 27 opened it. The momentum and centrifugal force of the hot burnt gases continues to force these gases to flow out the exhaust port 26, while the reduced pressure at the core C of the vortex V helps to suck in the intake air, which is directed to the center of the cylinder 21 through the intake port 27 in the piston head 28. The port 27 remains open during the intake process until the piston 20 moves up and closes the exhaust sleeve port 26, thereby reducing the pneumatic spring force on the piston 37 enough so that the inertia forces on the plate 20 force the valve 30 to close the port 27. The counter masses 45 and 46 are designed to balance out most of the inertia force on the plate-cylinder 32 so the pneumatic spring 37, 38 will not have to be as large and stiff as it would if the full inertia forces had to be resisted.

In FIG. 5, the piston 20 is shown moving up on its compression stroke, and the exhaust sleeve port 26 has just been closed. Also, the spring force on the intake valve mechanism 27 has been reduced sufficiently so that the inertia forces on the intake valve have forced it closed. As the piston 20 moved up on its compression stroke, the gas pressure in the cylinder 21 increased to a value where it acted on the plate 32 to hold the port 27 closed. The port 27 remains closed during the compression process and the expansion process and it does not open again until the exhaust position between the figures as described.

In addition to pneumatic and mechanical springs, there are other Ways of pressure-balancing and effecting the opening and closing of the valve 29. FIGS. 7-13 show a weight-operated system. The important function of the device shown in FIGS. 7-13 is to provide means for expanding the hot gases in the cylinder to a lower pressure before they are exhausted. This feature enables 20 to 40% more shaft power to be obtained from a given amount of fuel burnt.

In FIG. 7, a piston 50, generally similar to the piston 20, rigidly supports a valve 51 generally like the valve 30, which may be a rigid part of piston 20. A cylinderplate member 53 resembles the member 32 and has a valve port 54. The member 53 also has a pair of openings 55, 56 in which are engaged a pair of levers 57, 58, of counter masses 60, 61. The counter masses 60, 61 may b'e'pivotally mounted on the piston pin 52 for free swinging movement.

The cylinder-plate member 53 has a weight that will be called W and a mass equal to W /g. The two counter masses 60, 61 have a total weight W and a mass of W/g. The counter mass being preferably made in two sections 60 and 61, each section has half that amount.

The weight W may be considered to lie at a distance L from the center of the bore, while the center of gravity 62, 63' of each counter mass 60, 61 lies at a distance L from the center of the bore. The symbol X will be used to denote acceleration.

The counter masses W /g are designed so that the pressure in the engine cylinder 21 minus the pressure P in the crankcase, when multiplied by the valve area A, plus W L X/g is greater than W L X/g when the ex haust sleeve port is uncovered by the piston, the cylinder pressure is blown down. The pressures blow down until the equation is reversed and W L if/g is greater than W.L1X'

When this happens, the sleeve 53 moves and the intake port 54 is opened by movement of sleeve 53 away from valve 51, which is rigid in respect to piston 50 and a fresh charge of air flows into the engine cylinder 21. W X/g and W X/g are forces which act toward the crank end until the piston 50 moves past the half-stroke position while it is moving toward the head end. At that point, the forces W X/g and W X/g are reversed; since W L X g is greater than W L X/ g, the counter mass forces the intake valve closed so that air can be compressed in the engine cylinder. Since the valve mechanism is actuated by the motion of the piston and can'be lubricated by the oil system for the piston, it is much simpler than a cam tappet rocker arm system. The connecting rod 64 and counter masses 60, 61 may be pivotally mounted on a common piston pin and lubricated by the same system.

The operation of the two-cycle engine shown in FIGS. 7-13 is shown as follows in FIGS. 8-13:

- exhaust port 26. Intake gases continue to enter through the port 54 and to scavenge the exhaust gases. In FIG. 10 the piston 50 has moved toward the head, past the half stroke position and the counter masses 60 and 61 inertia forces act toward the head end and since therefore the intake valve 54 is closed by the valve member 51 and plate 66 on member 53.

From FIG. 10 to FIG. 11 the trapped gases are compressed. In FIG. 11 the piston 50 approaches the head 22, and combustion takes place in the precombustion chamber 23 (FIG. 12) and hot gases are forced out from the nozzle 24 to generate a vortex for scavenging action. Then the hot gases expand and do work on the piston 50, first with the ports 26 and 54 closed, as in FIG. 13, until the exhaust sleeve port 54 is opened again as in FIG. 7.

One important feature of the invention is that it improves the efticiency and performance of two-cycle engines. The novel fluid pumping means scavenges the cylinders more efficiently than the present systems and accelerates the flow of the fresh charge of air into the cylinders, so that the system makes a two-cycle engine approximately as elficient as a comparable four-cycle engine.

Another feature of the invention is that it makes the piston engine more efiicient by expanding the hot gases to a lower pressure in the cylinder 21 before they are exhausted; thus 20 to 40% more shaft energy can be obtained for a given amount of fuel energy added. A brief review of the Otto cycle and the diesel cycle as shown in FIGS. 14-17 shows how this accomplished.

This additional expansion is accomplished by having the exhaust and intake ports 26, 27 or 26, 54 remain open during the first half of the piston stroke during the pistons movement toward the head end of the cylinder, so that the cylinder can be scavenged and charged with fresh air during this portion of the cycle as shown by a to b on the FIGS. 14 through 17 diagrams. The exhaust and intake ports are closed during the last half of the piston movement towards its head; thus the air is compressed during this portion of the stroke. This process is illustrated by be on the Otto and diesel cycle charts. The combustion process c-d is illustrated on the Otto and diesel cycle charts. The expansion process d-e is illustrated on the Otto and diesel cycle charts. After combustion and during the expansion stroke toward the crank,

end, the exhaust and sleeve ports remain closed until the piston gets near the crank end, when the exhaust port is opened. Thus the hot gases expand to a lower pressure and temperature and produce the additional work abfe and additional heat abfe. The present engine energy cycle is bcdf (area) while my engine has an energy cycle abode which may be 20 to 40% greater than bcdf. Thus for a given amount of fuel my engine may be 20 to 40% more efiicient than the present engines. This corresponds to the cycle prescribed where b to c is compression and d to e is expansion work and a-b is the scavenging part of the cycle. The energy added by the further expansion of the gases in this invention is found in the area b, j, e, and a of the Otto and diesel cycle pressure-volume diagrams (FIGS. 14 and 16) and in the area b, j, a in the cone sponding temperature-entropy diagrams (FIGS. 15 and 17).

The valve arrangement may be used without the vortex scavenging means or with it depending on the design requirements. The intake ports means may be located in the cylinder head and have a valve mechanism which is actuated by a conventional crank-driven poppet valve.

To those skilled in the art to which this invention relates, many changes inconstruction and Widely differing embodiments and applications of the invention will suggest themselves without departing from the spirit and scope of the invention. The disclosures and the description herein are purely illustrative and are not intended to be in any sense limiting.

I claim:

1. In a two-cycle engine having a cylinder with a head end and with sleeve exhaust ports spaced from said head end, and a piston reciprocable in said cylinder between a head-end position and a crank-end position, and fresh air-intake means, the improvement comprising a precombustion chamber adjacent to said head end of said cylinder with firing means and in communication with said cylinder through a nozzle located near the outer periphery of said cylinder head and directed to expel heated gases from said nozzle into said cylinder from said precombustion chamber in a circumferential direction, so that the heated gases create a vortex moving helically along the cylinder toward said sleeve exhaust ports while burning the cylinder gases and sending them along the helical vortex path, and flow means for enabling air to flow from said air-intake means into the center of said vortex and distant from said head.

2. The combination of claim 1 wherein said air-intake means and said flow means comprise a head on said piston and a port therethrough.

3. The combination of claim 1 wherein said air-intake means comprises sleeve ports more distant from said head end than said exhaust ports.

4. In a two-cycle engine having a cylinder with a head end and with sleeve exhaust ports spaced from said head end, and a piston reciprocable in said cylinder between a head-end position and a crank-end position, and fresh air-intake means, the improvement comprising a precombustion chamber adjacent to said head end of said cylinder with firing means and in communication with said cylinder through a nozzle located near the outer periphery of said cylinder head and directed to expel heated gases from said nozzle into said cylinder from said pre-combustion chamber in a circumferential direction, so that the heated gases create a vortex moving helically along the cylinder toward said sleeve exhaust ports while burning the cylinder gases and sending them along the helical vortex path, said piston having a plate-cylinder member reciprocable with respect thereto and movable with it and movable relatively to it and comprising a head for said piston with a central axial air-intake port therein, said piston also having a port-closure valve for opening and closing said port, mounted rigidly with respect to said piston, and means for moving said platecylinder to open and close said valve in accordance with the gas pressure in said cylinder.

5. The combination of claim 4, wherein said platecylinder includes at least one rod extending axially of said piston and having an auxiliary piston thereon and an auxiliary cylinder for said auxiliary piston rigidly mounted in the main said cylinder, to serve as a pneumatic spring urging opening of said air-intake port.

6. The combination of claim 5, wherein said platecylinder includes a counterweight means pivotally mounted to a pin bearing in said piston; said counterweight serving to relieve some of the inertia loads on said spring thus making it small.

7. The combination of claim 4 wherein said plate-cylinder movement relative to said piston is controlled by counterweight means pivotally mounted to a cross-member extending diametrically of said piston.

8. A device for generating a vortex in a two-cycle engine having an engine piston, a cylinder in which said piston reciprocates, a head for said cylinder; exhaust sleeve ports uncovered by said piston when it is near its crank end, comprising: a nozzle in said head for directing high velocity gases in a circumferential direction on a spiral path as said piston moves away from said head to generate a vortex that has its center of rotation along the axis through the center of said cylinder, said vortex forcing the working fluid in said cylinder to accelerate radially outward and expedite its exhausting through said exhaust ports, said vortex generating a reduced pressure at its core, which is at the center of said cylinder; and intake port means for directing a fresh charge of fluid into the center of said cylinder after said exhaust port has been opened; said reduced pressure at the core of said vortex expediting the charging of the engine cylinder with a fresh charge of fluid.

9. The device of claim 8 wherein said intake port means is located in the head of said piston so that the fresh charge flows from the crankcase of said piston through said intake port when it is opened at the crank end of said piston.

10. The device of claim 8 wherein said intake port means comprise sleeve ports in said cylinder which are opened by said piston when it is near its extreme crank end.

11. The device of claim 8 wherein there is a pre-combustion chamber connected to said nozzle, whereby a fresh charge of fluid is compressed in said cylinder and sent through said nozzle into said pre-combustion chamber during the compression stroke of said piston toward said head, means for exploding fuel into the compressed said charge at the end of said compression stroke in said pre-combustion chamber, the resultant fuel explosion being substantially a constant volume heating in said precombustion chamber so that its pressure is increased over that in said engine cylinder and this high pressure forces said gases to flow through said nozzle at a high velocity into said cylinder during the combustion and expansion stroke as said piston moves away from said head.

12. An intake port and valve combination in an engine piston head comprising a poppet valve that remains a rigid part of said piston and 'a ring port plate that moves with respect to said piston to open and close said port, spring means for opening said intake port when said piston is near its crank end; and means for holding said ring port plate closed to move with said piston for conditions other than the intake and charging process when said piston is near its crank end.

13. The combination of claim 12 in which the spring means is a pneumatic spring actuated by the reciprocating motion of said piston. V

14. The combination of claim 12 in which the port plate seats on the cylinder side of said piston so that the gas pressure in said cylinder holds it closed when the exhaust port of said cylinder is closed.

15. The combination of claim 14 wherein said ring port plate includes a counterweight means pivotally mounted to a pin bearing in said piston, said counterweight serving to reduce some of the inertia loads on said spring means.

16. A device for generating a vortex in a two-cycle engine, comprising an engine piston, a cylinder in which said piston reciprocates; a head for said cylinder, a precombustion chamber in said head connected to said cylinder by a nozzle, a fresh charge of fluid being compressed in said cylinder and through said nozzle into said precombustion chamber during the compression stroke of said piston toward said head, means for exploding fuel in said pro-combustion chamber at the end of said compression stroke, said fuel explosion being by substantially a constant volume heating in said pre-combustion chamber so that its pressure is increased over that in said engine cylinder, this high pressure then forcing said gases to flow through said nozzle at a high velocity into said cylinder; said nozzle having means for directing said high velocity gases in a circumferential direction on a spiral path as said piston moves away from said head to generate a vortex that has its center of rotation along the axis through the center of said cylinder, exhaust sleeve ports uncovered by said piston when it is near its crank end, said vortex forcing the working fluid in said cylinder .to accelerate radially outward and expedite its exhaust through said exhaust ports, said vortex generating a reduced pressure at its core which is at the center of said cylinder, intake port and valve means in said piston head, spring means for opening said intake port after said exhaust port has been opened when said piston is near its crank end, saidintake port means directing a fresh charge into the center of said cylinder where said reduced pressure at the core of said vortex expedites the charging of said cylinder with a fresh charge of fluid, said spring means closing said intake port after said piston moves toward its head to close said exhaust sleeve ports and compressing the fluid trapped in said cylinder, said compression fluid acting on said intake volume and port plate to hold it closed while said exhaust port is closed.

17. A two-cycle engine having at least one cylinder with a piston reciprocating in each cylinder between a crank end and a head end; intake and exhaust port means for exhausting, scavenging and charging the cylinder as the piston moves from its crank end to near midstroke as it moves toward its head end, means for closing said port means for compression of a gaseous charge in said cylinder as said piston moves from its midstroke to its head end, means for exploding fuel in said cylinder to heat said compressed gaseous charge so that said heated charge expands in said cylinder and does work on said piston for the stroke from the head end to the crank end as said port means remain closed, and means for opening said exhaust and intake port means when said piston is near its crank end, said piston again returning to said head end and repeating its cycle.

18. The device in claim 17 wherein said exhaust port means is a sleeve port near the crank end which is opened and closed by the piston.

19. The device of claim 17 wherein said intake port means is located in the piston and has a valve mechanism which is actuated by the inertia forces on the mechanism.

20. The device of claim 17 wherein the intake port means is located in the cylinder head and has a valve mechanism and a crank driven poppet valve for actuating said valve mechanism.

21. The device of claim 17 wherein the pre-combustion chamber is arranged to produce a vortex with its axis along the center line of the cylinder, said vortex helping to expedite the scavenging to charging of said cylinder.

22. A piston with an inertia operated valve in its head comprising a port in the piston and a plate that is moved with respect to the piston by an inertia mechanism to open said port; pressure means for holding said plate closed against said port as said piston moves from a head end toward a crank end, exhaust port means for relieving the pressure in said cylinder as said piston is near its crank end; a counter inertia mass pivotally mounted on said piston, said counter inertia mass having means for lifting said plate away from the piston port when said exhaust port means are open, said means for lifting helping to close and hold closed said plate when said piston is in the position between its midstroke and its head end.

23. The device of claim 22 wherein said valve plate is a washer with a hole in its center and said port in said piston head is an annular hole.

24. The device of claim 22 wherein said piston has exhaust ports on the circumference near its head end and an exhaust passage in the piston connecting the said exhaust ports with the cylinder gases when said plate cylinder is open.

References Cited UNITED STATES PATENTS 810,495 1/1906 Miller ..123-73 LAURENCE M. GOODRIDGE, Primary Examiner. 

1. IN A TWO-CYCLE ENGINE HAVING A CYLINDER WITH A HEAD END AND WITH SLEEVE EXHAUST PORTS SPACED FROM SAID HEAD END, AND A PISTON RECIPROCABLE IN SAID CYLINDER BETWEEN A HEAD-END POSITION AND A CRANK-END POSITION, AND FRESH AIR-INTAKE MEANS, THE IMPROVEMENT COMPRISING A PRECOMBUSTION CHAMBER ADJACENT TO SAID HEAD END OF SAID CYLINDER WITH FIRING MEANS AND IN COMMUNICATION WITH SAID CYLINDER THROUGH A NOZZLE LOCATED NEAR THE OUTER PERIPHERY OF SAID CYLINDER HEAD AND DIRECTED TO EXPEL HEATED GASES FROM SAID NOZZLE INTO SAID CYLINDER FROM SAID PRECOMBUSTION CHAMBER IN A CIRCUMFERENTIAL DIRECTION, SO THAT THE HEATED GASES CREATE A VORTEX MOVING HELICALLY ALONG THE CYLINDER TOWARD SAID SLEEVE EXHAUST PORTS WHILE BURNING THE CYLINDER GASES AND SENDING THEM ALONG THE HELICAL VORTEX PATH, AND FLOW MEANS FOR ENABLING AIR TO FLOW FROM SAID AIR-INTAKE MEANS INTO THE CENTER OF SAID VORTEX AND DISTANT FROM SAID HEAD. 